1. Field of the Invention
The present invention relates to paging message transmission and reception, and more particularly, to a method of transmitting and receiving a paging message in a mobile communication system. Although the present invention is suitable for a wide scope of applications, it is particularly suitable for enhancing power efficiency of a terminal that receives a paging message by waking up in a paging listening interval.
2. Discussion of the Related Art
Generally, a terminal in an idle mode which does not have a traffic channel in a mobile communication system checks a presence or non-presence of paging in a manner of receiving a paging message with a predetermined interval. In doing so, a network has to be aware of a location of the terminal to transmit a paging message to the corresponding terminal in the idle mode. Yet, the tracking of the location of the idle-mode terminal by a cell unit is not preferable in that a new registration message should be transmitted each time the terminal moves away into another cell.
Due to the above reason, a plurality of cells are generally grouped together to be used a location tracking unit of a terminal in the idle mode. In the following description, an area corresponding to a unit of location tracking of an idle-mode terminal is named a paging area. In UMTS (Universal Mobile Telecommunication System), the paging area can be called a routing area.
In case that a paging area is changed, an idle-mode terminal sends a message for updating a location to a network. In case of attempting to page the idle-mode terminal, the network broadcasts a paging message carrying an identifier of the terminal to all cells belonging to a paging area reported by the idle-mode terminal most lately.
A time interval between two consecutive wake-up periods is called a paging period. If a paging period is raised to reduce power consumption of a terminal, a paging standby duration is increased. This is not suitable for newly generated services such as push-to-talk and the like. The newly generated services can request a very short paging standby duration, e.g., a period equal to or smaller than one second to provide a user with a feeling of an instant response for example. Preferably, a paging period for minimizing a call setup time in a push-to-talk system may amount to about 100 ms.
In the following description, explained is an operation of a terminal in the idle mode during a paging listening interval for receiving a paging message of a broadband wireless access system.
First of all, since a terminal in the idle mode is unable to receive a paging message from a base station, the terminal wakes up for a paging listening interval to receive a paging message. Hence, in case that the terminal receives a paging message including its MAC address from a base station during a paging listening interval, the terminal receives information included in the paging message and is then able to perform a corresponding operation such as a network entry and the like.
FIG. 1 is a diagram for a paging message transmitting and receiving process on a time axis according to a related art. In FIG. 1, a paging listening interval includes five frames for example. Assume that a paging message is received in the third frame.
Since a terminal is unable to know an exact frame on which a paging message is transmitted among five frames, it has to check all the frames. As a paging message including a MAC address of the terminal is received on the third frame) the terminal check the frames up to the third and then takes a corresponding action according to paging information included in the third frame.
If a paging message including the MAC address of the terminal does not exist in any of the five frames, the terminal enters an idle mode again without taking any action as soon as the five frames end. The terminal then performs the above operation repeatedly in a next paging listening interval.
However, according to the above-described method, a terminal in the idle mode has to check all frames within a paging listening interval even if a MAC address of a terminal is not included. Therefore, the power saving effect is degraded.